This invention relates to a semiconductor laser element.
Recently, semiconductor laser elements have been widely used in fields relating to optical communication systems such as Local Area Networks (LAN) or Cable Television (CATV). For example, the semiconductor laser element is incorporated into a small-sized optical module and is used as a light source in the optical communication system.
A conventional semiconductor laser element of the type described comprises a semiconductor block which has a first end surface, a second end surface, and a principal surface. The second end surface is opposite to the first end surface while the principal surface is contiguous to the first and the second end surfaces. The first and the second end surfaces serve as a laser beam emitting surface, respectively. With this structure, an optical resonator is provided between the first and the second end surfaces. In the conventional semiconductor laser element, the semiconductor block is about 300 .mu.m long. This means that the optical resonator should have the same length as the semiconductor block.
In order to manufacture the above-mentioned optical module, the semiconductor laser element is mounted and supported on an optical circuit board or a heat sink and is optically connected to an optical fiber or waveguide.
In such an assembly process, a large difficulty often arises in coupling an optical axis of the optical fiber or waveguide with the laser beam emitting surface. In other words, it is difficult for the semiconductor laser element to be readily mounted on the optical circuit board or the heat sink and be optically connected to the optical fiber or waveguide precisely. As the result, a yield in the assembly process is inevitably not so good.
Further, the conventional semiconductor laser element is usually poor at high-temperature operation. Specifically, it cannot operate with a low driving current in a high-temperature condition. Accordingly, a complicated electric circuit is necessary to control the driving current in the high-temperature condition.